Danionella cerebrum is translucent and no longer than about 12 millimeters, yet males can make pulses measuring more than 140 decibels at a distance of 10 to 12 millimeters. High-speed imaging revealed the trick: a specialized rib, fatigue-resistant muscle, and piece of drumming cartilage that accelerates at more than 2,000 g before striking the swim bladder. Researchers think the calls help the fish communicate in the shallow, cloudy waters of Myanmar. A fish shorter than a fingernail has turned its skeleton into percussion.